Cage and roller assembly

ABSTRACT

A cage and roller assembly includes rollers to be brought into rolling contact with a raceway surface provided on the outer periphery of a shaft, and an annular cage that retains the rollers. Lubricating oil is supplied through an oil supply hole that is provided inside the shaft and is open at an axial center region of the raceway surface. The cage includes annular portions having guide surfaces that are brought into contact with an inner peripheral surface of an outer member that is brought into rolling contact with the rollers, and cage bars that couple the annular portions together and are arranged with intervals in a circumferential direction. Clearances formed between the cage bars and the rollers housed in the pockets are larger in axial center portions of the cage bars between axial ends of the cage bars than at the axial ends of the cage bars.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-059683 filed onMar. 27, 2018 including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a cage and roller assembly including aplurality of rollers and an annular cage that retains the rollers.

2. Description of the Related Art

There is known a transmission including a planetary gearing mechanismin, for example, automobiles. FIG. 9 is a sectional view illustrating aplanetary gear 90 provided in the planetary gearing mechanism, and asupport structure 100 for the planetary gear 90. The support structure100 includes a carrier (support member) 91 and a cage and rollerassembly 92. The carrier 91 includes a disc-shaped body 93, a shaft 94,and a retaining member 95. A base 94 a of the shaft 94 is fixed to thebody 93. The retaining member 95 is attached to a tip 94 b of the shaft94. The annular planetary gear 90 is provided between the body 93 andthe retaining member 95. The planetary gear 90 rotates about the shaft94. In order to smooth the rotation, the cage and roller assembly 92 isprovided between the planetary gear 90 and the shaft 94 (see, forexample, Japanese Patent Application Publication No. 2009-8139 (JP2009-8139 A)). The cage and roller assembly 92 includes a plurality ofrollers 96 and an annular cage 97. The rollers 96 are brought intorolling contact with a raceway surface 94 c provided on the outerperiphery of the shaft 94. The cage 97 retains the rollers 96.

When the planetary gear 90 rotates, the rollers 96 are brought intorolling contact with the raceway surface 94 c provided on the outerperiphery of the shaft 94, and with a raceway surface 90 c provided onthe inner periphery of the planetary gear 90. With this structure, thecage 97 rotates together with the rollers 96. At this time, an outerperipheral surface 101 a of an annular portion 101 of the cage 97 isbrought into sliding contact with an inner peripheral surface 90 d ofthe planetary gear 90. The cage 97 is thus guided by the planetary gear90 and can rotate stably along the inner peripheral surface 90 d. Sincethe cage 97 is guided by the outer peripheral surface 101 a of theannular portion 101, the outer peripheral surface 101 is considered as aguide surface.

In the planetary gearing mechanism illustrated in FIG. 9, the cage androller assembly 92 is supplied with lubricating oil through an oilsupply hole 99 that is provided inside the shaft 94 and is open at anaxial center region of the raceway surface 94 c.

As described above, the outer peripheral surface 101 a of the annularportion 101 of the cage 97, that is, the guide surface, is brought intosliding contact with the inner peripheral surface 90 d of the planetarygear 90. In this view, it is necessary to supply the lubricating oil tothe space between the guide surface and the inner peripheral surface 90d of the planetary gear 90. As illustrated in FIG. 9, however, thelubricating oil is supplied to the cage and roller assembly 92 from theshaft 94 side on the inner periphery thereof. Therefore, the lubricatingoil is less likely to reach the guide surface (outer peripheral surface101 a) of the annular portion 101, which may cause lack of lubricatingoil.

SUMMARY OF THE INVENTION

It is one object of the present invention to facilitate lubricating oilsupplied from the inner peripheral side of the cage and roller assemblyto be supplied to the outer peripheral side of the cage and rollerassembly.

A cage and roller assembly according to one aspect of the presentinvention has the following features in its structure. That is, the cageand roller assembly includes a plurality of rollers and an annular cage.The rollers are brought into rolling contact with a raceway surfaceprovided on an outer periphery of a shaft. The cage retains the rollers.The cage and roller assembly is supplied with lubricating oil through anoil supply hole that is provided inside the shaft and is open at anaxial center region of the raceway surface. The cage includes a pair ofannular portions and a plurality of cage bars. The pair of annularportions has guide surfaces that can be brought into contact with aninner peripheral surface of an outer member that is brought into rollingcontact with the rollers. The cage bars couple the pair of annularportions together and are arranged with intervals in a circumferentialdirection. The rollers are housed in pockets each formed between thepair of annular portions and between the cage bars that are adjacent toeach other in the circumferential direction. Clearances formed betweenthe cage bars and the rollers housed in the pockets are larger in axialcenter portions of the cage bars between axial ends of the cage barsthan at the axial ends of the cage bars.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and further features and advantages of the invention willbecome apparent from the following description of example embodimentswith reference to the accompanying drawings, wherein like numerals areused to represent like elements and wherein:

FIG. 1 is a sectional view illustrating a planetary gear and a supportstructure for the planetary gear;

FIG. 2 is a perspective view of a cage and roller assembly;

FIG. 3 is a sectional view illustrating a part of a cage;

FIG. 4 is a sectional view of cage bars at their cage bar bodies;

FIG. 5 is a sectional view of the cage bars at their detachmentpreventing portions;

FIG. 6 is an illustration of the cage that is viewed from an axiallyouter side;

FIG. 7 is a sectional view of cage bars (other form) at their cage barbodies;

FIG. 8 is a sectional view illustrating an axial center portion of thecage bar and rollers; and

FIG. 9 is a sectional view illustrating a planetary gear and a supportstructure for the planetary gear according to related art.

DETAILED DESCRIPTION OF EMBODIMENTS

A cage and roller assembly of the present invention is applied tovarious rotary devices. A cage and roller assembly 20 in the formdescribed herein is included in a support structure 9 that supports aplanetary gear 10 provided in a planetary gearing mechanism. FIG. 1 is asectional view illustrating the planetary gear 10 and the supportstructure 9 for the planetary gear 10.

The support structure 9 includes a carrier (support member) 11 and thecage and roller assembly 20. The carrier 11 includes a disc-shaped body12, a shaft 13, and a retaining member 14. The shaft 13 has a circularshape in cross section. A base 13 a of the shaft 13 is fixed to the body12. The retaining member 14 is attached to a tip 13 b of the shaft 13.The annular planetary gear 10 is provided between the body 12 and theretaining member 14. The planetary gear 10 rotates about the shaft 13.In order to smooth the rotation, the cage and roller assembly 20 isprovided between the planetary gear 10 and the shaft 13. A central axisof the cage and roller assembly 20 coincides with a central axis of theshaft 13. The shaft 13 is a linear member having a fixed shape in crosssection along an axial direction. In this embodiment, the “axialdirection” is a direction along a central axis C0 of the cage and rollerassembly 20 (shaft 13). Any direction parallel to the central axis C0 isalso referred to as the axial direction.

The cage and roller assembly 20 includes a plurality of rollers 21 andan annular cage 22. The cage 22 retains the rollers 21. The axialdimensions of the planetary gear 10 and the cage 22 are substantiallyequal to each other. A side washer 15 is provided between the body 12and each of the cage and roller assembly 20 and the planetary gear 10.Another side washer 15 is provided between the retaining member 14 andeach of the cage and roller assembly 20 and the planetary gear 10. Theside washer 15 is a mating member where a face 27 of the cage 22 may bebrought into contact.

The shaft 13 is provided with a first hole 16 and a second hole 17. Thefirst hole 16 extends in the axial direction. The second hole 17 extendsin a radial direction from a part of the first hole 16. The second hole17 is open at the outer peripheral surface of the shaft 13. The outerperipheral surface of the shaft 13 includes a raceway surface 18. Therollers 21 are brought into rolling contact with the raceway surface 18.The raceway surface 18 is hereinafter referred to as “inner racewaysurface 18”. The inner peripheral surface of the planetary gear 10serves as a raceway surface 19. The rollers 21 are brought into rollingcontact with the raceway surface 19. The raceway surface 19 ishereinafter referred to as “outer raceway surface 19”. Althoughillustration is omitted, a tubular member (bush) may be provided on theinner periphery of the planetary gear 10. In this case, the innerperipheral surface of the tubular member serves as the outer racewaysurface 19. The first hole 16 is supplied with lubricating oil. Thelubricating oil flows through the second hole 17, and is supplied to thecage and roller assembly 20 through an opening 18 a on the inner racewaysurface 18 of the shaft 13. The lubricating oil is used for lubricatingthe cage and roller assembly 20. That is, the cage and roller assembly20 is supplied with the lubricating oil through oil supply holes (firsthole 16 and second hole 17) that are provided inside the shaft 13 andare open at the inner raceway surface 18. The second hole 17 (opening 18a) is open at an axial center region of the inner raceway surface 18.The axial center region is located at the same position in the axialdirection as that of an axial center portion of the cage and rollerassembly 20.

As described above, the cage and roller assembly 20 includes the rollers21 and the cage 22. The cage and roller assembly 20 of this embodimentdoes not include an inner ring and an outer ring that are provided in ageneral rolling bearing (for example, a cylindrical roller bearing).When the cage and roller assembly 20 rotates, the rollers 21 are broughtinto rolling contact with the inner raceway surface 18 provided on theouter periphery of the shaft 13 and the outer raceway surface 19provided on the inner periphery of the planetary gear 10. Althoughillustration is omitted, the cage and roller assembly of the presentinvention may have a structure including the outer ring.

FIG. 2 is a perspective view of the cage and roller assembly 20illustrated in FIG. 1. The roller 21 is a needle roller having a shapeof an elongated column. The cage 22 includes a pair of annular portions23 and 23 and a plurality of cage bars 24. The annular portions 23 and23 are provided away from each other in the axial direction. The cagebars 24 are arranged with intervals in a circumferential direction, andcouple the annular portions 23 and 23 together. Pockets 25 are eachprovided between the annular portions 23 and 23 and betweencircumferentially adjacent cage bars 24 and 24. One roller 21 is housedin each pocket 25. The roller 21 is formed of steel (for example,bearing steel). The cage 22 is formed of a resin (for example, apolyphenylene sulfide resin: PPS).

The annular portion 23 on one side in the axial direction and theannular portion 23 on the other side in the axial direction aresymmetrical on the right and left (one side and the other side in theaxial direction) but have the same shape. All the cage bars 24 have thesame shape as well. In each annular portion 23, a side closer to thepocket 25 in the axial direction is referred to as “axially inner side”,and a side opposite to the pocket 25 in the axial direction is referredto as “axially outer side”. FIG. 3 is a sectional view illustrating apart of the cage 22 (right part in FIG. 2). An annular recess 26 isformed on the axially outer side of the annular portion 23 (right sidein FIG. 3). The annular recess 26 is formed on a radially inner side ofthe annular portion 23. Therefore, the annular portion 23 has an annularprotrusion 28 on its radially outer side. The annular recess 26 and theannular protrusion 28 are formed continuously over the entirecircumference. The face 27 (first face 27) of the annular protrusion 28on the axially outer side is a contact surface that may be brought intocontact with the side washer 15. A face 29 (second face 29) of theannular recess 26 on the axially outer side is kept out of contact withthe side washer 15. Both the first face 27 and the second face 29 arering-shaped surfaces. A cylindrical surface is provided between thefirst face 27 and the second face 29. The cylindrical surface is aninner peripheral surface 30 of the annular protrusion 28.

A clearance is provided between the pocket 25 (see FIG. 2) provided inthe cage 22 and the roller 21. Therefore, the cage 22 and the roller 21can slightly be displaced relative to each other in the radialdirection. When the cage 22 is displaced in the radial direction in astate in which the cage and roller assembly 20 is attached between theshaft 13 and the planetary gear 10, an outer peripheral surface 31 ofeach annular portion 23 is brought into contact with an inner peripheralsurface 32 (outer raceway surface 19) of the planetary gear 10 (see FIG.3). An inner peripheral surface 33 of the annular portion 23 cannot bebrought into contact with an outer peripheral surface 34 (inner racewaysurface 18) of the shaft 13. In order to achieve this structure, aradial clearance e1 formed between the inner peripheral surface 32 ofthe planetary gear 10 and the outer peripheral surface 31 of the annularportion 23 is set smaller than a radial clearance e2 formed between theinner peripheral surface 33 of the annular portion 23 and the outerperipheral surface 34 of the shaft 13 (e 1<e2) in a state in which theplanetary gear 10 and the cage 22 are arranged concentrically. Theclearance e2 is 0.5 millimeters or smaller, and the clearance e1 issmaller than the clearance e2 (0.5 millimeters e2>e1). With thisstructure, the outer peripheral surface 31 of the annular portion 23 isbrought into sliding contact with the inner peripheral surface 32 of theplanetary gear 10 when the cage and roller assembly 20 rotates.Therefore, the cage 22 can stably rotate along the inner peripheralsurface 32 by being guided by the planetary gear 10. That is, theguiding method for the cage 22 of this embodiment is a method in whichthe cage 22 is guided by a member (planetary gear 10) located on aradially outer side of the cage 22. The cage 22 is guided by the outerperipheral surface 31 of the annular portion 23, and therefore the outerperipheral surface 31 is referred to as “guide surface 31” in thefollowing description.

For example, when an operation of attaching the cage and roller assembly20 to an inner peripheral side of the planetary gear 10 is performed andwhen the cage and roller assembly 20 is transported alone, it isnecessary that the roller 21 housed in the pocket 25 (see FIG. 2) beprevented from detaching radially outward or radially inward from thepocket 25. In view of this, each cage bar 24 of the cage 22 hasdetachment preventing portions 41 that prevent the roller 21 fromdetaching from the pocket 25. The detachment preventing portions 41 areprovided on both sides of the cage bar 24 in the axial direction. Eachcage bar 24 has a cage bar body 42 between the detachment preventingportions 41 and 41 on both sides in the axial direction. The cage barbody 42 has an oil reservoir bottom face 43 on its radially outer side.The function of the oil reservoir bottom face 43 is described later. InFIG. 2, the axial length of the cage bar body 42 is J1, and the axiallength of the detachment preventing portion 41 is J2. The cage bar body42 is longer in the axial direction than the sum of the axial lengths ofthe detachment preventing portions 41 located on both sides in the axialdirection (J1>2×J2). The detachment of the roller 21 is prevented suchthat a part of the detachment preventing portion 41 is brought intocontact with the end of the roller 21 from the radially outer side orthe radially inner side.

As described above, an axial center portion of the cage bar 24 that islocated between the two ends (detachment preventing portions 41 and 41)is the cage bar body 42. A large clearance G1 (see FIG. 4) is formedbetween the cage bar body 42 and the roller 21. A clearance G2 (see FIG.5) smaller than the clearance G1 is formed between the detachmentpreventing portion 41 and the roller 21. Therefore, when the roller 21and the cage 22 move relative to each other, the roller 21 is broughtinto contact with the detachment preventing portions 41 and 41, but iskept out of contact with the cage bar body 42. FIG. 4 is a sectionalview of the cage bars 24 at their cage bar bodies 42. FIG. 5 is asectional view of the cage bars 24 at their detachment preventingportions 41.

As illustrated in FIG. 2 and FIG. 5, each detachment preventing portion41 has outer claws 40 a on its radially outer portion 41 a. The outerclaw 40 a protrudes radially outward with respect to the cage bar body42, and also protrudes in the circumferential direction. Since the outerclaw 40 a protrudes in the circumferential direction, the radially outerportion 41 a has a shape that expands in the circumferential directionas compared to the cage bar body 42. The detachment preventing portion41 also has inner claws 40 b on its radially inner portion 41 b. Theinner claw 40 b protrudes in the circumferential direction. Since theinner claw 40 b protrudes in the circumferential direction, the radiallyinner portion 41 b has a shape that expands in the circumferentialdirection as compared to the cage bar body 42. A distance B1 between theouter claw 40 a on one side in the circumferential direction and theouter claw 40 a on the other side in the circumferential directionacross the pocket 25 is smaller than a diameter D of the roller 21(B1<D). A distance B2 between the inner claw 40 b on one side in thecircumferential direction and the inner claw 40 b on the other side inthe circumferential direction across the pocket 25 is smaller than thediameter D of the roller 21 (B2<D). The roller 21 is interposed, with adistance, between the outer claw 40 a and the inner claw 40 b located onthe radially inner side of the outer claw 40 a. Therefore, the roller 21does not detach radially outward or radially inward from the pocket 25.In order to house the roller 21 in the pocket 25, the roller 21 is movedcloser to the pocket 25 from the radially outer side, and is pressed toelastically deform the outer claw 40 a. As illustrated in FIG. 2, arecess 47 is provided between the outer claw 40 a and the annularportion 23, and the outer claw 40 a is not continuous with the annularportion 23 (not connected to the annular portion 23). This structurefacilitates the elastic deformation of the outer claw 40 a.

The radially outer portion 41 a including the outer claws 40 a protrudesradially outward with respect to the oil reservoir bottom face 43 of thecage bar body 42. The protruding region falls within the range of thedetachment preventing portion 41, and the axial length of the protrudingregion is J2. In this embodiment, the radially outer portion 41 aincluding the outer claws 40 a and the radially inner portion 41 bincluding the inner claws 40 b have the same axial length.

As illustrated in FIG. 4, the sectional shape of each cage bar body 42(sectional shape in cross section orthogonal to the axial direction) isa trapezoidal shape having a long side located on its radially outerside. The radially outer surface of the cage bar body 42 serves as theoil reservoir bottom face 43 located on the radially inner side withrespect to the guide surface 31 (see FIG. 2). The function of the oilreservoir bottom face 43 is described later. As illustrated in FIG. 3, aspace K is formed between the oil reservoir bottom face 43 and the outerraceway surface 19 of the planetary gear 10. The lubricating oil can bestored in the space K.

FIG. 4 and FIG. 5 illustrate a state in which a central axis of a pitchdiameter of a set of the rollers 21 coincides with a central axis of thecage 22 and the roller 21 (central axis C1 of the roller 21) is locatedat a middle point in the circumferential direction between a pair ofcircumferentially adjacent cage bars 24 (in the pocket 25). This stateis referred to as “reference state”. When the cage 22 and the roller 21in the reference state move relative to each other in thecircumferential direction, the roller 21 is brought into contact with apart of the cage bar 24. The part of the cage bar 24 where the roller 21is brought into contact is the detachment preventing portion 41. Eventhrough the relative movement, the roller 21 is not brought into contactwith the cage bar body 42. That is, if the roller 21 is skewed oradvances with a delay in the pocket 25 of the cage 22, the roller 21 isbrought into contact with the detachment preventing portion 41 at anaxial end. The posture of the roller 21 is maintained at both axialends. Thus, the posture of the roller 21 is stable in the pocket 25.

The cage and roller assembly 20 of this embodiment has a first axialguide structure. With the first axial guide structure, the lubricatingoil supplied through the opening 18 a on the inner raceway surface 18 ofthe shaft 13 (see FIG. 1) is guided to both sides in the axial directionalong the radially inner surface of the cage 22 and is supplied to thefaces (27, 29) on both sides in the axial direction. The cage and rollerassembly 20 of this embodiment also has a radial guide structure. Withthe radial guide structure, the lubricating oil supplied through theopening 18 a passes radially outward through a space between the cagebar 24 of the cage 22 and the roller 21 and is supplied to the space K(see FIG. 3) between the cage bar 24 and the planetary gear 10. The cageand roller assembly 20 of this embodiment also has a second axial guidestructure. With the second axial guide structure, the lubricating oil inthe space K is supplied to a space between the guide surface 31 of theannular portion 23 and the inner peripheral surface 32 of the planetarygear 10. The guide structures are described below.

The first axial guide structure is described below. As illustrated inFIG. 2 and FIG. 3, an inner recessed groove 36 is formed on a radiallyinner surface 35 of each cage bar 24. The inner recessed groove 36 isprovided over the total length of the cage bar 24, and is also formed onthe inner peripheral surface 33 of each annular portion 23. The radiallyinner surface 35 and the inner peripheral surface 33 have shapesconforming to a common imaginary cylindrical surface. The inner recessedgroove 36 continues from the radially inner surface 35, and extendsthrough the inner peripheral portion of the annular portion 23 (portionincluding the inner peripheral surface 33) in the axial direction.Therefore, the inner recessed groove 36 is open at the second face 29.The position on the second face 29 where the inner recessed groove 36 isopen corresponds to an open end 37. In this embodiment, the radiallyinner surface 35 of the cage bar body 42 is an imaginary surface becausethe inner recessed groove 36 is formed over the substantially entireradially inner surface 35.

FIG. 6 is an illustration of the cage 22 that is viewed from the axiallyouter side. In FIG. 6, the inner peripheral surface 32 of the planetarygear 10 and the outer peripheral surface 34 of the shaft 13 arerepresented by long dashed double-short dashed lines. The groove shape(sectional shape) of each inner recessed groove 36 is an arc shape. Thegroove shape of the inner recessed groove 36 on the second face 29 (openend 37) is also an arc shape. The long dashed short dashed lineillustrated in FIG. 6 represents an imaginary circumscribed circle Q1passing through groove bottoms of the plurality of inner recessedgrooves 36. A diameter L2 of the inner peripheral surface 30 of theannular protrusion 28 is larger than a diameter L1 of the imaginarycircumscribed circle Q1 (L2>L1). Therefore, the second face 29 has(first) flat surface portions 39 on both sides of the open end 37 ofeach inner recessed groove 36 in the circumferential direction, and a(second) flat surface portion 38 on a radially outer side of the openend 37. The diameter L1 and the diameter L2 are values on the secondface 29. The groove shape of the inner recessed groove 36 may be a shapeother than the arc shape.

A radial dimension T1 of the first face 27 of the annular protrusion 28is 50% or more of a radial dimension T0 of the annular portion 23. Theupper limit of the radial dimension T1 is 75% of the radial dimensionT0. That is, the radial dimension T1 is 50% or more and 75% or less ofthe radial dimension T0. The radial dimension T1 of the first face 27corresponds to a difference between the radius of the outer peripheralsurface (guide surface) 31 of the annular portion 23 and the radius ofthe inner peripheral surface 30 of the annular protrusion 28. The radialdimension T0 of the annular portion 23 corresponds to a differencebetween the radius of the outer peripheral surface (guide surface) 31and the radius of the inner peripheral surface 33.

A specific example of the size of the cage and roller assembly 20 isdescribed. In this embodiment, an outside diameter L3 of the cage 22(outside diameter of the annular portion 23) is 10 millimeters. Theradial dimension T1 of the first face 27 of the annular protrusion 28 is1 millimeter. The size of the cage 22 (outside diameter L3) may bechanged to any value. Even if the size of the cage 22 is changed, theradial dimension T1 of the first face 27 is preferably 1 millimeter orlarger. That is, L3−L2 is preferably 2 millimeters or larger (L3−L2≥2millimeters).

As described above (see FIG. 3), the radially inner surface 35 of thecage bar 24 and the inner peripheral surface 33 of the annular portion23 have shapes conforming to the common imaginary cylindrical surface. Adifference (r1−r2) between a radius r1 of an imaginary inscribed circlepassing through the radially inner surfaces 35 of the cage bars 24 and aradius r2 of the shaft 13 is a value equal to that of the clearance e2.The difference (r1−r2) between the radius r1 of the imaginary inscribedcircle and the radius r2 of the shaft 13 is 0.5 millimeters or smaller.That is, the clearance e2 formed between the radially inner surface 35of the cage bar 24 and the shaft 13 is larger than the clearance e1 onthe planetary gear 10 side (see FIG. 3 and FIG. 6), but is 0.5millimeters or smaller (e2≤0.5 millimeters). Thus, the clearance e2 issmall.

As described above, the cage 22 (see FIG. 2 and FIG. 3) provided in thecage and roller assembly 20 of this embodiment has the inner recessedgrooves 36. The inner recessed groove 36 is provided on the radiallyinner surface 35 of each cage bar 24, and extends through each annularportion 23 (its inner peripheral portion) in the axial direction.According to the cage and roller assembly 20, the lubricating oilsupplied through the oil supply holes 16 and 17 that are open at theinner raceway surface 18 of the shaft 13 (see FIG. 1) is guided in theaxial direction through the inner recessed grooves 36 to reach the faces27 and 29 of the annular portions 23. Therefore, even if the cage 22 isbrought into contact with the side washer 15 located axially adjacent tothe cage 22, a temperature increase can be suppressed and a frictionalresistance can be reduced by the lubricating oil that reaches the face27 of the annular portion 23.

The cage 22 has the annular recesses 26 and the annular protrusions 28at the axial ends. The annular recess 26 is provided on the axiallyouter side and the radially inner side of the annular portion 23, andthe inner recessed groove 36 is open at the annular recess 26. Theannular protrusion 28 is provided on the radially outer side of theannular recess 26, and has the first face 27 that may be brought intocontact with the side washer 15 located axially adjacent to the cage 22.With this structure, the lubricating oil guided in the axial directionthrough the inner recessed groove 36 enters the annular recess 26, andis stored in the annular recess 26. The lubricating oil in the annularrecess 26 can gradually enter a space between the first face 27 and theside washer 15, and is used for lubrication. Since the lubricating oilis stored in the annular recess 26, the lubricity between the cage 22and the side washer 15 can be stabilized over a long period.

As illustrated in FIG. 6, the diameter L2 of the inner peripheralsurface 30 of the annular protrusion 28 is larger than the diameter L1of the imaginary circumscribed circle Q1 passing through the groovebottoms of the inner recessed grooves 36 (L2>L1). Therefore, the secondface 29 where the inner recessed grooves 36 are open has the flatsurface portion 38 on the radially outer side of the open ends 37 of theinner recessed grooves 36. The lubricating oil guided in the axialdirection through each inner recessed groove 36 to enter the annularrecess 26 is likely to flow radially outward by a centrifugal force. Thelubricating oil flows radially outward along the flat surface portion 38as indicated by an arrow F1 in FIG. 6, and impinges on the innerperipheral surface 30 of the annular protrusion 28 to flow while thedirection is changed to the circumferential direction (arrows F2 in FIG.6). Thus, in the cage 22 of this embodiment, the lubricating oil iseasily stored in the annular recess 26.

In order to store the lubricating oil in the annular recess 26, it isonly necessary that the inner recessed grooves 36 be open at the secondface 29. Although illustration is omitted, the diameter L1 and thediameter L2 may be equal to each other (L1=L2). However, L2>L1 ispreferable as in this embodiment. If the diameter L1 and the diameter L2are equal to each other (L1=L2), the first flat surface portions 39 areformed on the second face 29 on both sides of each open end 37 in thecircumferential direction. However, the flat surface portion 38 is notformed on the radially outer side of the open end 37. If the flatsurface portion 38 is not formed on the radially outer side of the openend 37, a part of the lubricating oil supplied through the innerrecessed groove 36 is likely to flow directly toward the first face 27via the inner peripheral surface 30 of the annular protrusion 28 beforethe lubricating oil is stored in the annular recess 26. Thus, L2>L1(L2≠L1) is preferable in order that the lubricating oil that reaches theannular recess 26 through the inner recessed groove 36 is caused to flow(spread: arrows F2) in the circumferential direction to enhance thefunction of storing the lubricating oil in the annular recess 26.

In this embodiment, the radial dimension T1 of the first face 27 of theannular protrusion 28 is 50% or more of the radial dimension T0 of theannular portion 23. According to this structure, the first face 27 thatmay be brought into contact with the side washer 15 (see FIG. 3) is notnarrow. That is, the contact area between the annular portion 23 and theside washer 15 is secured in the annular portion 23. Particularly inthis embodiment, a problem arises in terms of wear of the cage 22 due tothe contact between the cage 22 and the side washer 15 if the cage 22 isformed of a resin and the side washer 15 is formed of a metal. Thestructure described above suppresses the wear of the cage 22 (annularportion 23).

In this embodiment (see FIG. 3 and FIG. 6), the difference (r1−r2)between the radius r1 of the imaginary inscribed circle passing throughthe radially inner surfaces 35 of the cage bars 24 and the radius r2 ofthe shaft 13 is 0.5 millimeters or smaller. According to this structure,the clearance e2 formed between the radially inner surface 35 of thecage bar 24 and the shaft 13 is small. Therefore, the lubricating oilpassing through the inner recessed groove 36 is covered with the outerperipheral surface 34 of the shaft 13 from the radially inner side. Thespace formed between the inner recessed groove 36 and the outerperipheral surface 34 of the shaft 13 serves as a passage of thelubricating oil. Through the passage, the lubricating oil is guided inthe axial direction. Thus, the lubricating oil reaches the faces 27 and29 of the annular portions 23 more easily.

As described above, in the first axial guide structure including theinner recessed grooves 36, the lubricating oil supplied through theopening 18 a on the inner raceway surface 18 (see FIG. 1) can be guidedto both sides in the axial direction along the radially inner surface ofthe cage 22 and supplied to the faces (27, 29) on both sides in theaxial direction. Therefore, a sliding resistance between the cage 22 andthe side washer 15 can be reduced, and heat generation can besuppressed. Thus, the cage and roller assembly 20 can have high rotationperformance. In this embodiment, the cage and roller assembly 20 havingthe structure described above is used in the support structure 9 thatsupports the planetary gear 10 (see FIG. 1). Thus, the temperatureincrease can be suppressed in the cage and roller assembly 20. Further,the torque of the planetary gearing mechanism can be reduced because thefrictional resistance is reduced.

The radial guide structure is described below. FIG. 4 is a sectionalview of the cage bars 24 at their cage bar bodies 42. FIG. 5 is asectional view of the cage bars 24 at their detachment preventingportions 41. In FIG. 4, the first clearance G1 is formed between thecage bar body 42 and the roller 21 located circumferentially adjacent tothe cage bar body 42 in the reference state. In FIG. 5, the secondclearance G2 is formed between the detachment preventing portion 41 andthe roller 21 located circumferentially adjacent to the detachmentpreventing portion 41 in the reference state.

In FIG. 4 and FIG. 5, the long dashed short dashed line represents animaginary plane Q2 passing through the central axis of the cage 22 andthe central axis C1 of the roller 21. In FIG. 4, the long dasheddouble-short dashed line represents an imaginary reference plane Q3parallel to the imaginary plane Q2. In the form illustrated in FIG. 4, aface 44 of the cage bar body 42 is provided along the imaginaryreference plane Q3. The minimum value of the clearance G1 is a minimumdistance g1 from the imaginary reference plane Q3 to the roller 21. Asillustrated in FIG. 5, the detachment preventing portion 41 has a secondface 55 located on the roller 21 side with respect to the face (firstface) 44 of the cage bar body 42. Therefore, the clearance G2 is smallerthan the clearance G1. More specifically, assuming that the minimumvalue (minimum distance) of the clearance G2 formed between thedetachment preventing portion 41 and the roller 21 is g2, the minimumvalue g2 is smaller than the minimum value (g1) of the clearance G1 (g2<g1). That is, the clearance (minimum value) formed between the cagebar 24 and the roller 21 located circumferentially adjacent to the cagebar 24 is larger in the cage bar body 42 at the axial center portion ofthe cage bar 24 than in the detachment preventing portions 41 providedat both axial ends of the cage bar 24. The minimum distance g1 ispreferably set to 0.3 millimeters or larger. The maximum value of theminimum distance g1 is 1 millimeter.

In FIG. 4, “A1” represents a distance between a radially outer end 46 ofthe cage bar body 42 provided in one cage bar 24 and a radially outerend 46 of the cage bar body 42 provided in the other cage bar 24 out ofthe pair of circumferentially adjacent cage bars 24 and 24. “A2”represents a distance between a radially inner end 45 of the cage barbody 42 provided in the one cage bar 24 and a radially inner end 45 ofthe cage bar body 42 provided in the other cage bar 24 out of the pairof cage bars 24 and 24. In the form illustrated in FIG. 4, the faces 44of the cage bar bodies 42 on both sides are provided along two imaginaryreference planes Q3 parallel to the imaginary plane Q2. The distance A1and the distance A2 are equal to each other (A1=A2). The distance A1 isa circumferential width of the pocket 25 on the radially outer side. Thedistance A2 is a circumferential width of the pocket 25 on the radiallyinner side.

Instead of the structure in which the distance A1 and the distance A2are equal to each other, the distance A2 may be larger than the distanceA1 (A2>A1). That is, in the cage bar bodies 42 having large clearancesG1 in the pair of circumferentially adjacent cage bars 24 and 24, it isonly necessary that the distance A2 between the radially inner ends 45and 45 be equal to or larger than the distance A1 between the radiallyouter ends 46 and 46 (A2≥A1).

Thus, in the cage and roller assembly 20 of this embodiment, thedistance between the cage bar bodies 42 and 42 is increased on theradially inner side. That is, it is only necessary that the minimumvalue of the distance A2 be the distance A1. In order to increase thedistance between the cage bar bodies 42 and 42 on the radially innerside, that is, to increase the distance A2, the faces 44 of the cage barbodies 42 may be inclined with respect to the imaginary reference planesQ3 as illustrated in FIG. 7. The inclination angle of the face 44 withrespect to the imaginary reference plane Q3 is θ (θ>0). In this case,the distance A2 on the radially inner side is larger than the distanceA1 on the radially outer side (A2≥A1). Thus, in the cage bar bodies 42in the form illustrated in FIG. 7, the faces 44 that face the outerperipheral surface of the roller 21 are inclined with respect to theimaginary reference planes Q3. In each cage bar 24 in the formsillustrated in FIG. 4 and FIG. 7, an intersection line obtained throughintersection of extension planes of the faces 44 on both sides in thecircumferential direction is located on the radially outer side withrespect to the central axis of the cage 22.

FIG. 8 is a sectional view illustrating the axial center portion of thecage bar 24 (that is, the cage bar body 42) and the rollers 21. Asdescribed above, the inner recessed groove 36 is formed on the radiallyinner surface 35 of the cage bar body 42. The inner recessed groove 36has a groove bottom face 48 and groove side faces 49. The groove bottomface 48 is a face on a deep side (radially outer side) of the innerrecessed groove 36. The groove side face 49 is a face extending radiallyinward from the groove bottom face 48. In the case of this embodiment,the groove shape of the inner recessed groove 36 is the arc shape, andthe groove bottom face 48 smoothly continues with the groove side faces49 and 49 on both sides of the groove bottom face 48. In the cage barbody 42, the groove width of the inner recessed groove 36 is(substantially) equal to the circumferential width dimension of theradially inner surface 35. The groove width of the inner recessed groove36 is a maximum distance between the groove side faces 49 and 49. Anacute apex 50 is interposed between one groove side face 49 and one face44 of the cage bar body 42. An acute apex 50 is also interposed betweenthe other groove side face 49 and the other face 44 of the cage bar body42. The face 44 and the groove side face 49 intersect each other at anacute angle. The intersecting portion (apex 50) may be chamfered orrounded. In this case, the extension plane of the face 44 and anextension plane of the groove side face 49 intersect each other at anacute angle. Thus, in the cage bar body 42, the face 44 that faces theouter peripheral surface of the roller 21 and the groove side face 49 ofthe inner recessed groove 36 continue with each other via the acute apex50.

As described above, in the cage and roller assembly 20 of thisembodiment (see FIG. 4 and FIG. 5), the clearance (minimum value) formedbetween the cage bar 24 and the roller 21 housed in the pocket 25 islarger in the axial center portion (cage bar body 42; see FIG. 4)between the axial ends (detachment preventing portions 41; see FIG. 5)than at the axial ends (G1>G2).

When the cage and roller assembly 20 rotates, the guide surface 31 ofthe annular portion 23 provided in the cage 22 may be brought intocontact with the inner peripheral surface 32 of the planetary gear 10.Therefore, it is necessary to supply the lubricating oil to the spacebetween the guide surface 31 and the inner peripheral surface 32 of theplanetary gear 10. In this embodiment (see FIG. 1), the lubricating oilis supplied to the cage and roller assembly 20 from the shaft 13 side onits inner periphery. In the cage and roller assembly 20 of thisembodiment, the lubricating oil supplied through the oil supply hole(second hole 17) that is open at the axial center region of the innerraceway surface 18 of the shaft 13 can flow radially outward through thespace between the cage bar 24 and the roller 21. As described above, theclearance formed between the cage bar 24 and the roller 21 is large inthe axial center portion. Therefore, the lubricating oil suppliedthrough the oil supply hole (second hole 17) easily reaches an outerperipheral side of the cage 22.

More specifically, in this embodiment (see FIG. 2), each cage bar 24 hasthe detachment preventing portions 41 on both sides in the axialdirection. The detachment preventing portion 41 has the outer claw 40 aand the inner claw 40 b between which the end of the roller 21 isinterposed with a distance on the radially outer side and the radiallyinner side. The lubricating oil hardly flows in the radial directionthrough a space between the detachment preventing portion 41 and theroller 21 due to the outer claw 40 a and the inner claw 40 b. In thisembodiment, the clearance formed between the roller 21 and the cage barbody 42 excluding the detachment preventing portion 41 (see FIG. 4) islarger than the clearance formed between the roller 21 and thedetachment preventing portion 41 (see FIG. 5) as described above(G1>G2). Therefore, the lubricating oil supplied through the oil supplyhole (second hole 17) that is open at the axial center region of theshaft 13 (see FIG. 1) easily reaches the outer peripheral side of thecage 22.

As described above, even when the lubricating oil is supplied to theinner peripheral side of the cage and roller assembly 20, thelubricating oil easily reaches the outer peripheral side of the cage 22(space K; see FIG. 3) by passing through the cage 22 in the radialdirection. Then, the lubricating oil is supplied to the space betweenthe guide surface 31 and the inner peripheral surface 32 of theplanetary gear 10. Thus, the cage and roller assembly 20 can have highrotation performance.

The cage bar body 42 is longer in the axial direction than the sum ofthe axial lengths (J2; see FIG. 2) of the detachment preventing portions41 located on both sides in the axial direction (J1>2×J2). Therefore,the range in which the clearance from the roller 21 is large is wide inthe axial direction. Thus, the lubricating oil supplied through the oilsupply hole (second hole 17) easily reaches the outer peripheral side ofthe cage 22.

In this embodiment, each detachment preventing portion 41 is providedwith an outer recessed groove 51 as illustrated in FIG. 2 thoughdescription is given later in the second axial guide structure. Theouter recessed groove 51 serves as a passage for causing the lubricatingoil to flow toward the guide surface 31 of the annular portion 23 fromthe oil reservoir bottom face 43 through the radially outer portion 41 aof the detachment preventing portion 41. With the outer recessed groove51, the lubricating oil stored in the space between the oil reservoirbottom face 43 and the inner peripheral surface 32 of the planetary gear10 (space K; see FIG. 3) is easily supplied to the guide surface 31through the outer recessed groove 51.

In the axial center portions (cage bar bodies 42) having largeclearances G1 (see FIG. 4 and FIG. 7) in the pair of circumferentiallyadjacent cage bars 24 and 24, the distance A2 between the radially innerends 45 and 45 is equal to or larger than the distance A1 between theradially outer ends 46 and 46 (A2≥A1). According to this structure, theradially inner opening of the pocket 25 is widened. Therefore, thelubricating oil supplied from the shaft 13 side is easily received onthe inner peripheral side of the cage 22. As a result, the lubricatingoil reaches the outer peripheral side of the cage 22 more easily.

Particularly in the form illustrated in FIG. 7, the faces 44 areinclined with respect to the imaginary reference planes Q3 in the axialcenter portions (cage bar bodies 42) having large clearances G1. Withthis structure, the distance A2 is larger than the distance A1 (A2>A1)in the axial center portions (cage bar bodies 42) having largeclearances G1 in the pair of circumferentially adjacent cage bars 24 and24. That is, the radially inner opening of the pocket 25 is wider thanthe radially outer opening of the pocket 25. Thus, the lubricating oilsupplied from the shaft 13 side is received on the inner peripheral sideof the cage 22 more easily.

In FIG. 7, the inclination angle of the face 44 with respect to theimaginary reference plane Q3 is θ. If the inclination angle θ increases,it is possible to enhance the performance of the cage 22 that receivesthe lubricating oil into each pocket 25. If the inclination angle θincreases excessively, however, the sectional area of each cage bar body42 decreases, and the strength may decrease. Although illustration isomitted, the cage 22 is manufactured by injection molding that uses asplit mold. The split mold includes mold parts configured to move in theradial direction (radially) in order to form the pockets 25. If theinclination angle θ increases, the mold parts may be difficult to movein the radial direction during mold removal (need to be removedforcibly). Thus, the upper limit value of θ is preferably about 5°(0≤θ<5°).

In this embodiment, the inner recessed grooves 36 are provided on theinner peripheral side of the cage 22. As described with reference toFIG. 8, in the cage bar body 42, the face 44 that faces the outerperipheral surface of the roller 21 and the groove side face 49 of theinner recessed groove 36 continue with each other via the acute apex 50.According to this structure, if a part of the lubricating oil flows outof the inner recessed groove 36 during the rotation of the cage androller assembly 20, the part of the lubricating oil can immediately flowradially outward along the face 44 via the acute apex 50 by thecentrifugal force. As a result, the part of the lubricating oil easilyreaches the outer peripheral side of the cage 22. That is, thelubricating oil flowing out of the inner recessed groove 36 can easilyflow radially outward along the face 44.

As described above, in the radial guide structure including thestructure in which the clearance G1 (see FIG. 4 and FIG. 7) between theroller 21 and the axial center portion (cage bar body 42) of the cagebar 24 provided in the cage 22 is increased, the lubricating oilsupplied from the inner peripheral side of the cage and roller assembly20 can be supplied to the space K (see FIG. 3) between the cage bar 24and the inner peripheral surface 32 of the planetary gear 10 by passingradially outward through the space between the cage bar 24 and theroller 21. Then, the lubricating oil is supplied to the space betweenthe guide surface 31 and the inner peripheral surface 32 of theplanetary gear 10. Thus, a sliding resistance can be reduced, and heatgeneration can be suppressed. Accordingly, the cage and roller assembly20 can have high rotation performance.

The second axial guide structure is described below. As described above(see FIG. 3), the cage 22 is provided with the oil reservoir bottom face43 on the radially outer side of each cage bar body 42. The lubricatingoil is stored in the space K between the oil reservoir bottom face 43and the inner peripheral surface 32 of the planetary gear 10. Theradially outer portion 41 a of each detachment preventing portion 41 isprovided between the oil reservoir bottom face 43 and the guide surface31 of the annular portion 23. The radially outer portion 41 a is aportion that protrudes toward the inner peripheral surface 32 of theplanetary gear 10 with respect to the oil reservoir bottom face 43.Therefore, the radially outer portion 41 a is an obstacle to thelubricating oil that is stored in the space K and is likely to flowtoward the guide surface 31. In view of this, the radially outer portion41 a is provided with the outer recessed groove 51 as the passage forcausing the lubricating oil to flow toward the guide surface 31 from thespace K (see FIG. 2 and FIG. 3). The groove shape (sectional shape) ofthe outer recessed groove 51 of this embodiment is an arc shape. Thegroove shape of the outer recessed groove 51 may be a shape other thanthe arc shape.

In the cage bar 24, the oil reservoir bottom face 43 and the outerrecessed groove 51 are continuously provided side by side in the axialdirection. The outer recessed groove 51 and the annular portion 23 arealso continuously provided side by side in the axial direction. The oilreservoir bottom face 43 and a bottom 51 a (see FIG. 3) of the outerrecessed groove 51 are located at the same position in the radialdirection. The guide surface 31 is located on the radially outer sidewith respect to the bottom 51 a of the outer recessed groove 51. In therange of the outer recessed groove 51, an inclined surface 53 isprovided between the bottom 51 a and the guide surface 31. That is, theinclined surface 53 is a surface connected to the guide surface 31 fromthe bottom 51 a of the outer recessed groove 51. The inclined surface 53is a surface extending radially outward with decreasing distance fromthe annular portion 23.

Description is given of the radially outer portion 41 a having the outerrecessed groove 51. The radially outer portion 41 a has the outer claws40 a. The outer claw 40 a is located on the radially outer side withrespect to the oil reservoir bottom face 43, and protrudes in thecircumferential direction to cover a part of the roller 21 from theradially outer side. Thus, the radially outer portion 41 a including theouter claws 40 a is located relatively on the radially outer side, butits position is limited. That is, a radially outer surface 52 of theradially outer portion 41 a is located on the radially inner side withrespect to the guide surface 31. The outer recessed groove 51 isrecessed from the radially outer surface 52.

As described above, the cage and roller assembly 20 of this embodimenthas the following structure. For example, when the cage 22 and therollers 21 are transported as a unit, it is necessary that the rollers21 be prevented from detaching from the pockets 25 of the cage 22. Inview of this, the detachment preventing portions 41 are provided on bothsides of each cage bar 24 of the cage 22 in the axial direction. Thedetachment preventing portion 41 has the outer claw 40 a that covers apart of the roller 21 from the radially outer side. In order to guidethe rotation of the cage 22, the guide surface 31 of each annularportion 23 may be brought into contact with the inner peripheral surface32 of the planetary gear 10. Therefore, it is necessary to supply thelubricating oil to the space between the guide surface 31 and the innerperipheral surface 32 of the planetary gear 10. The cage bar body 42 ofthe cage bar 24 has the oil reservoir bottom face 43 on its radiallyouter side. The oil reservoir bottom face 43 is located on the radiallyinner side with respect to the guide surface 31. According to thisstructure, the lubricating oil is stored in the space between the oilreservoir bottom face 43 and the inner peripheral surface 32 of theplanetary gear 10. In the cage and roller assembly 20, the detachmentpreventing portions 41 are provided on both sides of the oil reservoirbottom face 43 in the axial direction. The detachment preventing portion41 may keep the lubricating oil stored on the oil reservoir bottom face43 from being supplied to the guide surface 31.

As the second axial guide structure, each detachment preventing portion41 is provided with the outer recessed groove 51. The outer recessedgroove 51 constitutes the passage for causing the lubricating oil toflow toward the guide surface 31 from the oil reservoir bottom face 43through the radially outer portion 41 a of the detachment preventingportion 41. Therefore, the lubricating oil stored in the space betweenthe oil reservoir bottom face 43 and the inner peripheral surface 32 ofthe planetary gear 10 is supplied to the guide surface 31 through theouter recessed groove 51. As a result, the cage and roller assembly 20can have high rotation performance.

As described above, in the cage and roller assembly 20 of thisembodiment, the lubricating oil is supplied through the oil supply hole(second hole 17) that is open at the axial center region of the innerraceway surface 18 provided in the shaft 13 (see FIG. 1). Thelubricating oil supplied through the oil supply hole (second hole 17)can flow radially outward through the space between the cage bar 24 ofthe cage 22 and the roller 21. As described in the radial guidestructure, the clearance (minimum value) formed between the cage bar 24and the roller 21 housed in the pocket 25 is larger in the cage bar body42 at the center in the axial direction than in the detachmentpreventing portions 41 on both sides in the axial direction. Therefore,the lubricating oil supplied through the oil supply hole (second hole17) easily reaches the outer peripheral side of the cage 22 through thespace between the cage bar body 42 and the roller 21. As describedabove, even when the lubricating oil is supplied to the inner peripheralside of the cage and roller assembly 20, the lubricating oil can reachthe outer peripheral side of the cage 22 by passing through the cage 22in the radial direction. The lubricating oil is stored in the spacebetween the oil reservoir bottom face 43 and the inner peripheralsurface 32 of the planetary gear 10. Then, the stored lubricating oil issupplied to the guide surface 31 through the outer recessed groove 51.

As illustrated in FIG. 3, the oil reservoir bottom face 43 and thebottom 51 a of the outer recessed groove 51 are located at the sameposition in the radial direction. That is, the oil reservoir bottom face43 and the bottom 51 a of the outer recessed groove 51 are locatedcollinearly. Therefore, the lubricating oil stored in the space betweenthe oil reservoir bottom face 43 and the inner peripheral surface 32 ofthe planetary gear 10 easily flows along the bottom 51 a from the oilreservoir bottom face 43, that is, easily enters the outer recessedgroove 51. The outer recessed groove 51 has the inclined surface 53 as agroove terminal end face on the axially outer side. The inclined surface53 has a shape that extends radially outward with decreasing distancefrom the annular portion 23. Therefore, the lubricating oil present inthe outer recessed groove 51 is easily supplied to the guide surface 31.

As described above (see FIG. 2 and FIG. 3), the radially outer surface52 of the outer claw 40 a of the detachment preventing portion 41 islocated on the radially inner side with respect to the guide surface 31,and the outer recessed groove 51 is recessed from the radially outersurface 52. With this structure, a part of the lubricating oil in theouter recessed groove 51 is used for lubricating the end of the roller21. That is, on the periphery of the axial center portion of the roller21, a relatively large amount of lubricating oil is present owing to theoil reservoir bottom face 43. At the axial end of the roller 21,however, the lubricating oil hardly flows because the detachmentpreventing portion 41 is provided. Therefore, the amount of thelubricating oil may be smaller at the axial end of the roller 21 than atthe axial center portion of the roller 21. According to the structuredescribed above, the lubricating oil is easily guided to the axial endof the roller 21 from the outer recessed groove 51 via the radiallyouter surface 52 of the outer claw 40 a. For example, when the cage 22rotates at high speed, a part of the lubricating oil present in theouter recessed groove 51 may flow out of the outer recessed groove 51.When the part of the lubricating oil flows out of the outer recessedgroove 51 in the circumferential direction, the part of the lubricatingoil can pass through a space between the radially outer surface 52 ofthe outer claw 40 a and the inner peripheral surface 32 of the planetarygear 10 according to the structure described above. The part of thelubricating oil passing in this manner is used for lubricating the endof the roller 21. Thus, the lubricity can be increased also at the endof the roller 21.

Another advantage can be attained in the structure in which the radiallyouter portion 41 a provided in the detachment preventing portion 41 islocated on the radially inner side with respect to the guide surface 31.As described above, the outer claw 40 a is elastically deformed in orderto house the roller 21 in the pocket 25 during assembling of the cageand roller assembly 20. When the outer claw 40 a is elasticallydeformed, a part of the outer claw 40 a may plastically be deformedbeyond its elastic range. As an actual phenomenon, a part of the outerclaw 40 a may plastically be deformed so as to be warped radiallyoutward even when the roller 21 is inserted into the pocket 25 from theradially outer side while the outer claw 40 a is deformed. Even when thepart of the outer claw 40 a is plastically deformed, the occurrence of acase where the outer claw 40 a is located on the radially outer sidewith respect to the guide surface 31 can be reduced according to thestructure described above. Thus, a part of the cage 22 other than theguide surface 31 can be prevented from being brought into contact withthe inner peripheral surface 32 of the planetary gear 10.

As described above, in the second axial guide structure including theouter recessed grooves 51, the lubricating oil in the space K (see FIG.3) is easily supplied to the space between the guide surface 31 and theinner peripheral surface 32 of the planetary gear 10. As a result, thesliding resistance between the guide surface 31 and the inner peripheralsurface 32 of the planetary gear 10 can be reduced, and the heatgeneration can be suppressed. Thus, the cage and roller assembly 20 canhave high rotation performance. In this embodiment, the cage and rollerassembly 20 having the structure described above is used in the supportstructure 9 that supports the planetary gear 10 (see FIG. 1). Thus, thetemperature increase can be suppressed in the cage and roller assembly20. Further, the torque of the planetary gearing mechanism can bereduced because the frictional resistance is reduced.

The embodiment disclosed herein is illustrative but is not limitative inall respects. The scope of rights of the present invention is notlimited to the embodiment described above, but encompasses allmodifications within the scope of structures described in the claims andtheir equivalents. In the embodiment described above, description isgiven of the case where the cage and roller assembly 20 is included inthe support structure 9 that supports the planetary gear 10 provided inthe planetary gearing mechanism. The present invention is not limited tothis case. The cage and roller assembly of the present invention is alsoapplicable to other devices.

According to the cage and roller assembly of the present invention, evenif the lubricating oil is supplied to the inner peripheral side of thecage and roller assembly, the lubricating oil radially passes throughthe cage, thereby reaching the outer peripheral side of the cage.Therefore, the lubricating oil is easily supplied to the space betweenthe guide surface and the inner peripheral surface of the outer member.

What is claimed is:
 1. A cage and roller assembly, comprising: aplurality of rollers to be brought into rolling contact with a racewaysurface provided on an outer periphery of a shaft; and an annular cagethat retains the rollers, the cage and roller assembly being suppliedwith lubricating oil through an oil supply hole that is provided insidethe shaft and is open at an axial center region of the raceway surface,wherein the cage includes: a pair of annular portions having guidesurfaces that are brought into contact with an inner peripheral surfaceof an outer member that is brought into rolling contact with therollers; and a plurality of cage bars that couple the pair of annularportions together and are arranged with intervals in a circumferentialdirection, the rollers are housed in pockets each formed between thepair of annular portions and between the cage bars that are adjacent toeach other in the circumferential direction, clearances formed betweenthe cage bars and the rollers housed in the pockets are larger in axialcenter portions of the cage bars between axial ends of the cage barsthan at the axial ends of the cage bars, and in the axial centerportions of a pair of the circumferentially adjacent cage bars, whichhave the larger clearances, a distance between the radially inner endsis equal to or larger than a distance between the radially outer ends.2. The cage and roller assembly according to claim 1, wherein in each ofthe axial center portions having the larger clearances, a face of eachof the cage bars which faces an outer peripheral surface of thecorresponding one of the rollers is inclined with respect to animaginary reference plane parallel to an imaginary plane passing througha central axis of the cage and a central axis of the roller.
 3. The cageand roller assembly according to claim 2, wherein the cage bar has, ateach axial end of the cage bar, a detachment preventing portionincluding an outer claw and an inner claw between which the end of theroller is interposed with a distance on the radially outer side and theradially inner side, respectively, the cage bar further has, between thedetachment preventing portions at the axial ends of the cage bar, a cagebar body having an oil reservoir bottom face on the radially outer sideof the cage bar body, the oil reservoir bottom face located on theradially inner side with respect to the guide surface, and each of theclearances is larger in the cage bar body than in the detachmentpreventing portion.
 4. The cage and roller assembly according to claim3, wherein the detachment preventing portion is provided with an outerrecessed groove configured as a passage for causing the lubricating oilto flow toward the guide surface from the oil reservoir bottom facethrough the detachment preventing portion.
 5. The cage and rollerassembly according to claim 4, wherein the cage has an inner recessedgroove that is provided on a radially inner surface of the cage bar andextends through the annular portions in an axial direction, and the faceof the cage bar that faces the outer peripheral surface of the rollerand a groove side face of the inner recessed groove continue with eachother via an acute apex in the axial center portion of the cage bar. 6.The cage and roller assembly according to claim 3, wherein the cage hasan inner recessed groove that is provided on a radially inner surface ofthe cage bar and extends through the annular portions in an axialdirection, and the face of the cage bar that faces the outer peripheralsurface of the roller and a groove side face of the inner recessedgroove continue with each other via an acute apex in the axial centerportion of the cage bar.
 7. The cage and roller assembly according toclaim 2, wherein the cage has an inner recessed groove that is providedon a radially inner surface of the cage bar and extends through theannular portions in an axial direction, and the face of the cage barthat faces the outer peripheral surface of the roller and a groove sideface of the inner recessed groove continue with each other via an acuteapex in the axial center portion of the cage bar.
 8. A cage and rollerassembly, comprising: a plurality of rollers to be brought into rollingcontact with a raceway surface provided on an outer periphery of ashaft; and an annular cage that retains the rollers, the cage and rollerassembly being supplied with lubrication oil through an oil supply holethat is provided inside the shaft and is open at an axial center regionof the raceway surface, wherein the cage includes: a pair of annularportions having guide surfaces that are brought into contact with aninner peripheral surface of an outer member that is brought into rollingcontact with the rollers; and a plurality of cage bars that couple thepair of annular portions together and are arranged with intervals in acircumferential direction, the rollers are housed in pockets each formedbetween the pair of annular portions and between the cage bars that areadjacent to each other in the circumferential direction, clearancesformed between the cage bars and the rollers housed in the pockets arelarger in axial center portions of the cage bars between axial ends ofthe cage bars than at the axial ends of the cage bars, the cage bar has,at each axial end of the cage bar, a detachment preventing portionincluding an outer claw and an inner claw between which the end of theroller is interposed with a distance on the radially outer side and theradially inner side, respectively, and the cage bar further has, betweenthe detachment preventing portions at the axial ends of the cage bar, acage bar body having an oil reservoir bottom face on the radially outerside of the cage bar body, the oil reservoir bottom face located on theradially inner side with respect to the guide surface, and each of theclearances is larger in the cage bar body than in the detachmentpreventing portion.
 9. The cage and roller assembly according to claim8, wherein the detachment preventing portion is provided with an outerrecessed groove configured as a passage for causing the lubricating oilto flow toward the guide surface from the oil reservoir bottom facethrough the detachment preventing portion.
 10. The cage and rollerassembly according to claim 9, wherein the cage has an inner recessedgroove that is provided on a radially inner surface of the cage bar andextends through the annular portions in an axial direction, and the faceof the cage bar that faces the outer peripheral surface of the rollerand a groove side face of the inner recessed groove continue with eachother via an acute apex in the axial center portion of the cage bar. 11.The cage and roller assembly according to claim 8, wherein the cage hasan inner recessed groove that is provided on a radially inner surface ofthe cage bar and extends through the annular portions in an axialdirection, and the face of the cage bar that faces the outer peripheralsurface of the roller and a groove side face of the inner recessedgroove continue with each other via an acute apex in the axial centerportion of the cage bar.
 12. A cage and roller assembly, comprising aplurality of rollers to be brought into rolling contact with a racewaysurface provided on an outer periphery of a shaft; and an annular cagethat retains the rollers, the cage and roller assembly being suppliedwith lubricating oil through an oil supply hole that is provided insidethe shaft and is open at an axial center region of the raceway surface,wherein the cage includes: a pair of annular portions having guidesurfaces that are brought into contact with an inner peripheral surfaceof an outer member that is brought into rolling contact with therollers; and a plurality of cage bars that couple the pair of annularportions together and are arranged with intervals in a circumferentialdirection, the rollers are housed in pockets each formed between thepair of annular portions and between the cage bars that are adjacent toeach other in the circumferential direction, clearances formed betweenthe cage bars and the rollers housed in the pockets are larger in axialcenter portions of the cage bars between axial ends of the cage barsthan at the axial ends of the cage bars, the cage has an inner recessedgroove that is provided on a radially inner surface of the cage bar andextends through the annular portions in an axial direction, and the faceof the cage bar that faces the outer peripheral surface of the rollerand a groove side face of the inner recessed groove continue with eachother via an acute apex in the axial center portion of the cage bar. 13.The cage and roller assembly according to claim 12, wherein the cage hasan inner recessed groove that is provided on a radially inner surface ofthe cage bar and extends through the annular portions in an axialdirection, and the face of the cage bar that faces the outer peripheralsurface of the roller and a groove side face of the inner recessedgroove continue with each other via an acute apex in the axial centerportion of the cage bar.